I like cruseing. You just have to take it for what it is. They try their hardest to keep you well fed and entertained. There is food everywhere 24 hours a day. There is always a deck somewhere that’s empty no matter how many people are on board. There is plenty of opportunity for exercise and swimming. And there is usually a magic show somewhere on board every evening. Blow off the gambling and the time-constricting formal meals and just have a good time on your own schedule. I recall on the first night out of a cruise to Halifax sitting in a steam room drinking ice water, looking out of a picture window watching the sun set over the North Atlantic, and listening to Pavorati sing Nessus Dorma - not bad for $800 for a 7 day cruise for two.
Domestic (local) -> Domestic (further away) -> Cruises -> Lower and medium end travel to Caribbean and Europe -> Medium to higher end traveling to Caribbean and Europe -> World traveler
Some people stop along the way, either from budgeting issues, time availability, get nervous about not having your hand held during international travel, etc
But in your example - you almost certainly had to be in the entry level room with no view, drank zero/no alcohol, didn't do any off-boat tours, didn't use the internet, didn't tip much, etc, plus not including airfare + hotel on front/back end of trip by port to get to $800 (or you risk missing your cruise if flight is cancelled) - or you aren't including those in your $800 - all that needs to be added up and compared to other alternatives. Cruise ships love breaking it down this way because it gives the illusion of being cheaper than it really is
The last time I priced our a cruise - the cheapest I could find for my wife and I with 200+ sq ft, a view of the ocean, alcohol included with some internet and tips, not including air, hotel b/a, or tours off the cruise, was about $3.5k for the cheapest 7 night cruise I could find. For folks willing to stay in a 120-145 sq ft room for 7 nights and don't drink much alcohol, more power to you. I haven't been able to deal with that since I turned 30.
Lastly, yes anywhere you go you can find some privacy, but the popular areas are popular for a reason and are nearly always very busy on a cruise. Not true on most resorts.